1. Field of the Invention
This invention relates to improvements in overtemperature protectors for electrically heated appliances such as flat irons. More particularly, the invention relates to a pair of contacts held in circuit-making engagement by an electrical insulator-capped fusible pin, at least one of the contacts being spring-mounted.
2. Description of the Prior Art
In general, the use of fusible members in overtemperature protectors (also referred to in the art as "thermal cut-outs") is well-known. For example, U.S. Pat. Nos. 1,015,954; 1,150,973; 1,364,122; 1,382,101; 1,439,979; 1,468,418; and 1,556,762 show overtemperature protectors in connection with electric irons. Other appliances having overtemperature protectors of various types are disclosed in U.S. Pat. Nos. 1,615,742; 1,693,364; and 2,022,531. The earlier patents concerned with protection against thermal overloads generally disclose space consuming arrangements, usually spread out in a horizontal plane. Moreover, none of this art shows the overtemperature protector in combination with elements of a thermostatic control. For example, U.S. Pat. No. 1,150,973 discloses a heavy cantilevered spring running from the front to the rear of an iron and biased to eject the plug on the power supply cord, but restrained by an externally-located fusible button held on a stud in thermal contact with the heating element. Further, U.S. Pat. No. 1,382,101 discloses a heavy cantilevered spring extending over a major portion of the housing for an iron and being biased to eject an insulating washer having attached to it a conductive plate with lugs spanning a gap between the supply and utilization elements of the circuit. The washer is held on a spindle and restrained from executing the move urged by the spring because of a fusible pin passing through the spindle in the washer's path. Similarly, U.S. Pat. No. 1,439,979 shows an overtemperature protector with a torsion spring again supporting a jumper element spanning a gap between the supply and utilization elements of the circuit. The jumper element includes complex, multi-part linkage for over-center engaging of a ratchet wheel on a shaft having its end buried in fusible material, the engagement restraining the spring when the fusible material is in the solid phase.
As to the use of overtemperature protectors in an appliance having a thermostatic control, U.S. Pat. No. 3,665,152 discloses a biased spring made of a relatively high-resistance electrical conductor, which is joined to a lower-resistance conductor by use of a low-temperature solder, this thermally sensitive junction being a separate part of the circuit between one side of the power supply line, the thermostatic switch and the other side of the supply line.
Accordingly, there is need of an improved structure providing simpler, yet compact and reliable long-term protection against thermal overloads.